Commit-ID: b11e2e18a7fc8eaa3d592c260d50c7129e094ded
Gitweb: http://git.kernel.org/tip/b11e2e18a7fc8eaa3d592c260d50c7129e094ded
Author: Eric Biggers <ebiggers@xxxxxxxxxx>
AuthorDate: Sun, 24 Sep 2017 12:59:06 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 26 Sep 2017 09:43:46 +0200
x86/fpu: Use validate_xstate_header() to validate the xstate_header in __fpu__restore_sig()
Tighten the checks in __fpu__restore_sig() and update comments.
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Eric Biggers <ebiggers3@xxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Kevin Hao <haokexin@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Michael Halcrow <mhalcrow@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
Cc: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
Cc: kernel-hardening@xxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20170924105913.9157-4-mingo@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/kernel/fpu/signal.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index 7fa3bdb..fb639e7 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -214,8 +214,11 @@ sanitize_restored_xstate(struct task_struct *tsk,
struct xstate_header *header = &xsave->header;
if (use_xsave()) {
- /* These bits must be zero. */
- memset(header->reserved, 0, 48);
+ /*
+ * Note: we don't need to zero the reserved bits in the
+ * xstate_header here because we either didn't copy them at all,
+ * or we checked earlier that they aren't set.
+ */
/*
* Init the state that is not present in the memory
@@ -224,7 +227,7 @@ sanitize_restored_xstate(struct task_struct *tsk,
if (fx_only)
header->xfeatures = XFEATURE_MASK_FPSSE;
else
- header->xfeatures &= (xfeatures_mask & xfeatures);
+ header->xfeatures &= xfeatures;
}
if (use_fxsr()) {
@@ -308,7 +311,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
/*
* For 32-bit frames with fxstate, copy the user state to the
* thread's fpu state, reconstruct fxstate from the fsave
- * header. Sanitize the copied state etc.
+ * header. Validate and sanitize the copied state.
*/
struct fpu *fpu = &tsk->thread.fpu;
struct user_i387_ia32_struct env;
@@ -329,9 +332,8 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
} else {
err = __copy_from_user(&fpu->state.xsave, buf_fx, state_size);
- /* xcomp_bv must be 0 when using uncompacted format */
- if (!err && state_size > offsetof(struct xregs_state, header) && fpu->state.xsave.header.xcomp_bv)
- err = -EINVAL;
+ if (!err && state_size > offsetof(struct xregs_state, header))
+ err = validate_xstate_header(&fpu->state.xsave.header);
}
if (err || __copy_from_user(&env, buf, sizeof(env))) {
--
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